diff --cumulative is a sub-option of --dirstat

The option used to be implemented as if it is a totally independent one,
but "git diff --cumulative" would not mean anything without "--dirstat".

This makes --cumulative imply --dirstat.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff.c

@@ -1072,7 +1072,7 @@ static void show_dirstat(struct diff_options *options)
 	dir.alloc = 0;
 	dir.nr = 0;
 	dir.percent = options->dirstat_percent;
-	dir.cumulative = options->output_format & DIFF_FORMAT_CUMULATIVE;
+	dir.cumulative = DIFF_OPT_TST(options, DIRSTAT_CUMULATIVE);
 
 	changed = 0;
 	for (i = 0; i < q->nr; i++) {
@@ -2298,6 +2298,7 @@ void diff_setup(struct diff_options *options)
 	options->break_opt = -1;
 	options->rename_limit = -1;
 	options->dirstat_percent = 3;
+	DIFF_OPT_CLR(options, DIRSTAT_CUMULATIVE);
 	options->context = 3;
 
 	options->change = diff_change;
@@ -2470,8 +2471,10 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 		options->output_format |= DIFF_FORMAT_SHORTSTAT;
 	else if (opt_arg(arg, 'X', "dirstat", &options->dirstat_percent))
 		options->output_format |= DIFF_FORMAT_DIRSTAT;
-	else if (!strcmp(arg, "--cumulative"))
-		options->output_format |= DIFF_FORMAT_CUMULATIVE;
+	else if (!strcmp(arg, "--cumulative")) {
+		options->output_format |= DIFF_FORMAT_DIRSTAT;
+		DIFF_OPT_SET(options, DIRSTAT_CUMULATIVE);
+	}
 	else if (!strcmp(arg, "--check"))
 		options->output_format |= DIFF_FORMAT_CHECKDIFF;
 	else if (!strcmp(arg, "--summary"))

diff.h

@@ -31,7 +31,6 @@ typedef void (*diff_format_fn_t)(struct diff_queue_struct *q,
 #define DIFF_FORMAT_PATCH	0x0010
 #define DIFF_FORMAT_SHORTSTAT	0x0020
 #define DIFF_FORMAT_DIRSTAT	0x0040
-#define DIFF_FORMAT_CUMULATIVE	0x0080
 
 /* These override all above */
 #define DIFF_FORMAT_NAME	0x0100
@@ -64,6 +63,7 @@ typedef void (*diff_format_fn_t)(struct diff_queue_struct *q,
 #define DIFF_OPT_CHECK_FAILED        (1 << 16)
 #define DIFF_OPT_RELATIVE_NAME       (1 << 17)
 #define DIFF_OPT_IGNORE_SUBMODULES   (1 << 18)
+#define DIFF_OPT_DIRSTAT_CUMULATIVE  (1 << 19)
 #define DIFF_OPT_TST(opts, flag)    ((opts)->flags & DIFF_OPT_##flag)
 #define DIFF_OPT_SET(opts, flag)    ((opts)->flags |= DIFF_OPT_##flag)
 #define DIFF_OPT_CLR(opts, flag)    ((opts)->flags &= ~DIFF_OPT_##flag)